Probe contract system having planarity adjustment mechanism

ABSTRACT

A probe contact system is capable of adjusting distances between tips of the contactors and contact targets with simple and low cost mechanism. The probe contact system includes a contact substrate having a large number of contactors, a probe card for fixedly mounting the contact substrate for establishing electrical communication between the contactors and a test system, a probe card ring attached to a frame of the probe contact system for mechanically coupling the probe card to the frame, and a plurality of connection members for connecting the probe card to the probe card ring at three or more locations in which the connection member is adjustable for changing a gap between the probe card and the probe card ring.

[0001] This is a continuation-in-part of U.S. application Ser. No.09/583,837, filed May 31, 2000.

FIELD OF THE INVENTION

[0002] This invention relates to a semiconductor test system having alarge number of contactors for establishing electrical connection with asemiconductor device under test, and more particularly, to a probecontact system having a planarity adjustment mechanism for adjustingdistances between tips of the contactors and surfaces of contact targetssuch as contact pads of the semiconductor wafer under test.

BACKGROUND OF THE INVENTION

[0003] In testing high density and high speed electrical devices such asLSI and VLSI circuits, a high performance contact structure provided ona probe card must be used. A contact structure is basically formed of acontact substrate having a large number of contactors or probe elements.The contact substrate is mounted on a probe card for testing LSI andVLSI chips, semiconductor wafers, burn-in of semiconductor wafers anddice, testing and burn-in of packaged semiconductor devices, printedcircuit boards and the like. The present invention is directed to aprobe contact system including such a contact structure.

[0004] In the case where semiconductor devices to be tested are in theform of a semiconductor wafer, a semiconductor test system such as an ICtester is usually connected to a substrate handler, such as an automaticwafer prober, to automatically test the semiconductor wafer. Such anexample is shown in FIG. 1 in which a semiconductor test system has atest head 100 which is ordinarily in a separate housing and electricallyconnected to the test system with a bundle of cables 110. The test head100 and a substrate handler 400 are mechanically as well as electricallyconnected with one another with the aid of a manipulator 500 which isdriven by a motor 510. The semiconductor wafers to be tested areautomatically provided to a test position of the test head 100 by thesubstrate handler 400.

[0005] On the test head 100, the semiconductor wafer to be tested isprovided with test signals generated by the semiconductor test system.The resultant output signals from the semiconductor wafer under test (ICcircuits formed on the semiconductor wafer) are transmitted to thesemiconductor test system. In the semiconductor test system, the outputsignals are compared with expected data to determine whether the ICcircuits on the semiconductor wafer function correctly or not.

[0006] In FIG. 1, the test head 100 and the substrate handler 400 areconnected through an interface component 140 consisting of a performanceboard 120 (shown in FIG. 2) which is a printed circuit board havingelectric circuit connections unique to a test head's electricalfootprint, coaxial cables, pogo-pins and connectors. In FIG. 2, the testhead 100 includes a large number of printed circuit boards 150 whichcorrespond to the number of test channels (test pins) of thesemiconductor test system. Each of the printed circuit boards 150 has aconnector 160 to receive a corresponding contact terminal 121 of theperformance board 120. A “frog” ring 130 is mounted on the performanceboard 120 to accurately determine the contact position relative to thesubstrate handler 400. The frog ring 130 has a large number of contactpins 141, such as ZIF connectors or pogo-pins, connected to contactterminals 121, through coaxial cables 124.

[0007] As shown in FIG. 2, the test head 100 is placed over thesubstrate handler 400 and mechanically and electrically connected to thesubstrate handler through the interface component 140. In the substratehandler 400, a semiconductor wafer 300 to be tested is mounted on achuck 180. In this example, a probe card 170 is provided above thesemiconductor wafer 300 to be tested. The probe card 170 has a largenumber of probe contactors (such as cantilevers or needles) 190 tocontact with contact targets such as circuit terminals or contact padsin the IC circuit on the semiconductor wafer 300 under test.

[0008] Electrical terminals or contact receptacles (contact pads) of theprobe card 170 are electrically connected to the contact pins 141provided on the frog ring 130. The contact pins 141 are also connectedto the contact terminals 121 of the performance board 120 with thecoaxial cables 124 where each contact terminal 121 is connected to theprinted circuit board 150 of the test head 100. Further, the printedcircuit boards 150 are connected to the semiconductor test systemthrough the cable 110 having, for example, several hundreds of innercables.

[0009] Under this arrangement, the probe contactors 190 contact thesurface (contact targets) of the semiconductor wafer 300 on the chuck180 to apply test signals to the semiconductor wafer 300 and receive theresultant output signals from the wafer 300. The resultant outputsignals from the semiconductor wafer 300 under test are compared withthe expected data generated by the semiconductor test system todetermine whether the IC circuits on the semiconductor wafer 300performs properly.

[0010] A large number of contactors must be used in this type ofsemiconductor wafer test, such as from several hundreds to severalthousands. In such an arrangement, it is necessary to planarize the tipsof the contactors so that all of the contactors contact the contacttargets at substantially the same time and same pressure. Ifplanarization is not achieved, some contactors establish electricalconnections with corresponding contact targets while other contactorsfail to establish electrical connections, which is impossible toaccurately test the semiconductor wafer. To completely connect all ofthe contactors to the contact targets, the semiconductor wafer must befurther pressed against the probe card. This may physically damagesemiconductor dies which receive excessive pressure by contactors.

[0011] U.S. Pat. No. 5,861,759 shows an automatic probe cardplanarization system to planarize a first plane defined by a pluralityof contact points of a probe card and relative to a second plane definedby a top surface of a semiconductor wafer supported on a prober. Acamera is used to measure the height of at least three selected contactpoints on the probe card relative to the plane of wafer. Based on themeasured values, the position of the first plane relative to the secondplane is calculated.

[0012] With that information and the geometry of the prober and tester,the height variations necessary for the two height variable points aremade to planarize the first plane relative to the second plane. Thisconventional technology requires a camera for visualizing the height ofthe contact points, resulting in increase in cost and decrease inreliability of the overall system.

[0013] U.S. Pat. No. 5,974,662 shows a method of planarizing tips ofprobe elements of a probe card assembly. The probe elements are mounteddirectly on a space transformer (contact substrate). It is so configuredthat the orientation of the space transformer, and thus the orientationof the probe elements, can be adjusted without changing the orientationof the probe card. In this method, an electrically conductive metalplate (virtual wafer) is provided in stead of the target semiconductorwafer as a reference plane. A cable and a computer are also provided insuch a way that a computer display shows whether a conductive path iscreated or not for each probe tip relative to the metal plate by forexample, white and black dots.

[0014] Based on the visual image on the display, the planarity of theprobe tips is adjusted by rotating differential screws so that all ofthe probe tips make substantially simultaneous contact with the metalplate. Because this conventional technology uses a conductive metalplate to establish conductive path for all of probe elements, itrequires an extra time to mount the metal plate and replace the samewith the target semiconductor wafer. Further, because this method needsa computer and a display to illustrate the states of contact ornon-contact of the probe element, an overall cost has to be increased.

[0015] Under the circumstances, there is a need in the industry toincorporate a more simple and economical way in a probe contact systemto adjust the planarity of the contactors with respect to the surface ofthe semiconductor wafer.

SUMMARY OF THE INVENTION

[0016] Therefore, it is an object of the present invention to provide aprobe contact system having a planarity adjustment mechanism foradjusting distances between tips of contactors and a surface of asemiconductor device under test.

[0017] It is another object of the present invention to provide a probecontact system having a planarity adjustment mechanism and a contactstructure mounted on a probe card wherein the contact structure isformed of a contact substrate and a large number of contactors mountedon the contact substrate.

[0018] It is a further object of the present invention to provide aprobe contact system having a planarity adjustment mechanism foradjusting distances between a contact substrate and a semiconductorwafer under test so that all of contactors on the contact substratecontact the surface of the semiconductor wafer at the same time.

[0019] It is a further object of the present invention to provide aprobe contact system having a planarity adjustment mechanism foradjusting distances between a contact substrate and a semiconductorwafer under test so that each contactor exerts an identical pressureagainst the surface of the semiconductor wafer when brought into contactwith the semiconductor wafer.

[0020] In the present invention, a planarity adjustment mechanism for aprobe contact system for establishing electrical connection with contacttargets includes a contact substrate having a large number of contactorsmounted on a surface thereof, a probe card for mounting the contactsubstrate for establishing electrical communication between thecontactors and a test head of a semiconductor test system, means forfixedly mounting the contact substrate on the probe card, a probe cardring attached to a frame of the probe contact system for mechanicallycoupling the probe card to the frame, and a plurality of connectionmembers for connecting the probe card to the probe card ring at three ormore locations on the probe card in which the connection member isadjustable for changing a gap between the probe card and the probe cardring.

[0021] In a further aspect, the planarity adjustment mechanism furtherincludes a gap sensor for measuring a gap between the contact substrateand a target substrate at predetermined locations of the contactsubstrate where the target substrate includes a semiconductor wafer tobe tested and a reference plate prepared for adjusting the planarity,and a rotation adjustment device for adjusting the connection member sothat the gap between the probe card and the probe card ring isregulated, thereby adjusting the distances between the tips of thecontactors and the contact target to be identical to one another.

[0022] Preferably, the probe contact system includes a conductiveelastomer provided between the contact substrate and the probe card forelectrically connecting the contact substrate and the probe card, and asupport frame provided between the contact substrate and the conductiveelastomer for supporting the contact substrate wherein the connectionmember is extended between the probe card and the support frame.

[0023] In a further aspect of the present invention, the connectionmember for connecting the contact substrate and the probe card isconfigured by bolts and nuts, and the nuts are rotatably supported onthe surface of the probe card, and the rotation adjustment device havinga bottom opening which engages with the nut is placed on the surface ofthe probe card for rotating the nuts so that the gap between the contactsubstrate and the target substrate at each of the three locationsbecomes identical to one another.

[0024] In a further aspect of the present invention, the planarityadjustment mechanism is an automatic system for adjusting distancesbetween the contact substrate and the target substrate. The adjustmentmechanism includes motors for rotating the nuts based on control signalsfrom a controller. The controller produces the control signals bycalculating the measured gaps.

[0025] According to the present invention, the probe contact system iscapable of adjusting the distances between tips of contactors and thesurface of the semiconductor wafer under test or reference plate. Theplanarity adjustment mechanism is capable of adjusting the distancesbetween the contact substrate and the semiconductor wafer so that all ofcontactors on the contact substrate contact the surface of thesemiconductor wafer at substantially the same time with substantiallythe same pressure.

[0026] The planarity adjustment mechanism to be used in the probecontact system of the present invention includes the rotation adjustmentdevice for rotating the nuts on the probe card with fine steps therebyadjusting the distances between the contact substrate and thesemiconductor wafer easily and accurately. The planarity adjustmentmechanism of the present invention can be configured as an automaticsystem by incorporating the motors for driving the nuts on the probecard and the controller generating control signals for the motors on thebasis of the gaps measured by the gap sensors.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027]FIG. 1 is a schematic diagram showing a structural relationshipbetween a substrate handler and a semiconductor test system having atest head.

[0028]FIG. 2 is a diagram showing an example of detailed structure forconnecting the test head of the semiconductor test system to thesubstrate handler.

[0029]FIG. 3 is a cross sectional view showing an example of contactstructure having beam like (silicon finger) contactors to be mounted ona probe card of the probe contact system of the present invention.

[0030]FIG. 4 is a schematic diagram showing a bottom view of the contactstructure of FIG. 3 having a plurality of beam like contactors.

[0031]FIG. 5 is a cross sectional view showing an example of totalstack-up structure in a probe contact system using the contact structureof FIGS. 3 and 4 as an interface between the semiconductor device undertest and the test head of FIG. 2.

[0032]FIG. 6 is a cross sectional view showing an example of structureof a probe contact system having a planarity adjustment mechanism of thepresent invention.

[0033]FIG. 7 is a perspective view showing an upper surface of the probecard and a probe card ring used in the probe contact system of FIG. 6.

[0034] FIGS. 8A-8C are a top view, a front view and a bottom view,respectively, of a rotation adjustment device for use with the planarityadjustment mechanism of the present invention.

[0035] FIGS. 9A-9G are exploded views showing components and assemblythereof used in the rotation adjustment device of the present invention.

[0036]FIG. 10 is a perspective view showing an example of upper surfaceof the probe card having an arrangement for planarity adjustment incombination with the rotation adjustment device of the presentinvention.

[0037]FIG. 11 is a cross sectional view showing another example of probecontact system having a planarity adjustment mechanism of the presentinvention.

[0038]FIG. 12 is a perspective view showing an upper surface of theprobe card, a probe card ring and an intermediate ring used in the probecontact system of FIG. 11.

[0039]FIG. 13 is a cross sectional view showing a further example ofprobe contact system having a planarity adjustment mechanism of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

[0040] An example of contact structure to be used in the probe contactsystem of the present invention will be described with reference toFIGS. 3 and 4. Many other different types of contact structures are alsofeasible in the probe contact system of the present invention. A contactstructure 10 of FIG. 3 has beam like (silicon finger) contactors 30produced through a microfabrication technology such as a semiconductorproduction process.

[0041] The contact structure 10 is basically formed of a contactsubstrate 20 and the silicon finger contactors 30. The contact structure10 is so positioned over contact targets such as contact pads 320 on asemiconductor wafer 300 to be tested that the contactors 30 establishelectric connections with the semiconductor wafer 300 when pressed witheach other. Although only two contactors 30 are shown in FIG. 3, a largenumber, such as from several hundreds to several thousands, ofcontactors 30 are aligned on the contact substrate 20 in actualapplications such as semiconductor wafer testing.

[0042] Such a large number of contactors are produced through the samesemiconductor production process such as a photolithography process on asilicon substrate and mounted on the contact substrate 20 made, forexample of ceramic, silicon, alumina, glass fibers or other material.The pitch between the contact pads 320 may be as small as 50 μm or lesswherein the contactors 30 on the contact substrate 20 can easily bealigned in the same pitch since they are made through the samesemiconductor production process as the semiconductor wafer 300 aremade.

[0043] The silicon finger contactors 30 can be directly mounted on thecontact substrate 20 as shown in FIGS. 3 and 4 to form a contactstructure which can be mounted on the probe card 170 of FIG. 2. Sincethe silicon finger contactors 30 can be fabricated in a very small size,an operable frequency range of a contact structure or probe cardmounting the contactors of the present invention can be easily increasedto 2 GHz or higher. Because of the small size, the number of contactorson a probe card can be increased to as many as, for example 2,000 ormore, which is able to test as many as 32 or more memory devices inparallel at the same time.

[0044] In FIG. 3, each of the contactors 30 has a conductive layer 35 ina finger (beam) like shape. The contactor 30 also has a base 40 which isattached to the contact substrate 20. An interconnect trace 24 isconnected to the conductive layer 35 at the bottom of the contactsubstrate 20. Such a connection between the interconnect trace 24 andthe conductive layer 35 is made, for example, through a solder ball 28.The contact substrate 20 further includes a via hole 23 and an electrode22. The electrode 22 is to interconnect the contact substrate 20 to anexternal structure such as a pogo-pin block or an IC package through awire or a conductive elastomer.

[0045] Under this arrangement, when the semiconductor wafer 300 movesupward, the silicon finger contactors 30 and the contact targets 320 onthe wafer 300 mechanically and electrically contact with each other.Consequently, a signal path is established from the contact target 320to the electrodes 22 on the contact substrate 20. The interconnect trace24, the via hole 23 and the electrode 22 also function to fan-out thesmall pitch of the contactors 30 to a larger pitch to fit to theexternal structure such as a pogo-pin block or an IC package.

[0046] Because of the spring force of the beam like shape of the siliconfinger contactors 30, the end of the conductive layer 35 produces asufficient contact force when the semiconductor wafer 300 is pressedagainst the contact substrate 20. The end of the conductive layer 35 ispreferably sharpened to achieve a scrubbing effect when pressed againstthe contact target 320 for penetrating through a metal-oxide layer.

[0047] For example, if the contact target 320 on the semiconductor wafer300 has a metal-oxide layer such as formed with aluminum oxide on itssurface, the scrubbing effect is necessary to establish an electricalconnection the contact target 320 with low contact resistance. Thespring force derived from the beam like shape of the contactor 30provides an appropriate contact force against the contact target 320.The elasticity produced by the spring force of the silicon fingercontactor 30 also functions to compensate the differences in size orflatness (planarity) involved in the contact substrate 20, the contacttarget 320 and the wafer 300, as well as the contactors 30. However, itis still necessary to incorporate a planarity adjustment mechanism ofthe present invention to fully connect all of the contactors with thecontact targets at substantially the same time with the same pressure.

[0048] An example of material of the conductive layer 35 includesnickel, aluminum, copper, nickel palladium, rhodium, nickel gold,iridium or several other depositable materials. An example of size ofthe silicon finger contactor 30 intended for a semiconductor testapplication may be 100-500 μm in overall height, 100-600 μm inhorizontal length, and about 30-50 μm in width for the pitch of 50 μm ormore between contact targets 320.

[0049]FIG. 4 is a bottom view of the contact substrate 20 of FIG. 3having a plurality of silicon finger contactors 30. In an actual system,a larger number of contactors, such as several hundreds of them, will bealigned in the manner shown in FIG. 4. The interconnect traces 24 expandthe pitch of the contactors 30 to the pitch of the via holes 23 andelectrodes 22 as shown in FIG. 4. Adhesives 33 are provided at contactpoints (inner areas of contactors 30) between the substrate 20 and thebases 40 of the contactors 30. The adhesives 33 are also provided at thesides (top and bottom of contactors 30 in FIG. 4) of the set ofcontactors 30. An example of adhesives 33 includes thermosettingadhesives such as epoxies, polyimide and silicone, and thermoplasticadhesives such as acrylic, nylon, phenoxy and olefin, and UV curedadhesives.

[0050]FIG. 5 is a cross sectional view showing an example of totalstack-up structure forming a probe contact system using the contactstructure of FIGS. 3 and 4. The probe contact system will be used as aninterface between the semiconductor device under test and the test headof FIG. 2. In this example, the interface assembly includes a conductiveelastomer 50, a probe card 60, and a pogo-pin block (frog ring) 130provided over the contact structure 10 in the order shown in FIG. 5.

[0051] The conductive elastomer 50, probe card 60 and pogo-pin block 130are mechanically as well as electrically connected with one another.Thus, electrical paths are created from the tips of the contactors 30 tothe test head 100 through the cables 124 and performance board 120 (FIG.2). Thus, when the semiconductor wafer 300 and the probe contact systemare pressed with each other, electrical communication will beestablished between the device under test (contact pads 320 on thesemiconductor wafer 300) and the semiconductor test system.

[0052] The pogo-pin block (frog ring) 130 is equivalent to the one shownin FIG. 2 having a large number of flexible pins such as pogo-pins tointerface between the probe card 60 and the performance board 120. Atupper ends of the pogo-pins, cables 124 such as coaxial cables areconnected to transmits signals to printed circuit boards (pinelectronics cards) 150 in the test head 100 in FIG. 2 through theperformance board 120. The probe card 60 has a large number of contactpads or electrodes 62 and 65 on the upper and lower surfaces thereof.The electrodes 62 and 65 are connected through interconnect traces 63 tofan-out the pitch of the contact structure to meet the pitch of thepogo-pins in the pogo-pin block 130.

[0053] The conductive elastomer 50 is preferably provided between thecontact structure 10 and the probe card 60. By its elasticity, theconductive elastomer 50 is to ensure electrical communications betweenthe electrodes 22 of the contact structure and the electrodes 62 of theprobe card by compensating unevenness or vertical gaps therebetween. Theconductive elastomer 50 is an elastic sheet with unidirectionalconductivity by having a large number of conductive wires in a verticaldirection. For example, the conductive elastomer 250 is comprised of asilicon rubber sheet and a multiple rows of metal filaments. The metalfilaments (wires) are provided in the direction perpendicular to thehorizontal sheet of the conductive elastomer 250. An example of pitchbetween the metal filaments is 0.02 mm with thickness of the siliconrubber sheet is 0.2 mm. Such a conductive elastomer is produced byShin-Etsu Polymer Co. Ltd and available in the market.

[0054]FIG. 6 is a cross sectional view showing an example of structureof a probe contact system having a planarity adjustment mechanism of thepresent invention. The contact substrate 20 having a plurality ofcontactors 30 is mounted on the probe card 60 through a support frame 55and a conductive elastomer 50. The support frame 55 for supporting thecontact substrate 20 is fixedly connected to the probe card 60 byfastening means such as screws 250. Instead of the screws 250, variousother fastening means are also feasible for fixedly connecting the probecard 60 and the contact substrate 20. As described with reference toFIG. 5, the conductive elastomer 50 establishes electrical conductivityonly in the vertical direction, i.e., between the contact substrate 20and the probe card 60. The conductive elastomer 50 is preferable but canbe replaced with other means for connecting the electrodes 22 on theupper surface of the contact substrate 29 and the electrodes 62 on thelower surface of the probe card 60.

[0055] On the bottom surface of the contact substrate 20, electrodes 292are provided as a part of gap sensors. Alternatively, the electrodes 292will be formed on the bottom surface of the support frame 55. Theelectrodes 292 are provided at three or more locations on the bottomsurface of the contact substrate 20. Each location of the electrode 292is preferably close to an edge of the contact substrate 20 in such a wayto form vertexes of a triangular or polygonal shape.

[0056] The example of FIG. 6 further shows gap sensors 290 on thesemiconductor wafer 300 and a gap measurement instrument 280 whichreceives signals from the gap sensors 290. The gap sensors 290 are alsoelectrodes and are placed on the surface of the semiconductor wafer 300at positions corresponding to the electrodes 292 on the bottom surfaceof the contact substrate 20, i.e, at three or more locations thereon. Inthis example, the gap sensor is configured by a pair of electrodes 290and 292 forming a capacitor.

[0057] The relationship between the gap sensor 290 and the electrodes292 can be reversed. Namely, the gap sensor 290 can be provided on thebottom surface of the contact substrate and the electrode 292 can beprovided on the upper surface of the semiconductor wafer 300. Thesemiconductor wafer 300 may include conductive pads on its surface whichcan be used as the electrodes 292. Further, a reference plate made of,for example, metal, ceramic or alumina may be used in lieu of thecustomer wafer 300 so that the planarity of the probe contact system isadjusted by a manufacturer prior to the shipment to customers.

[0058] The probe card 60 is mounted on a frame 240 of the probe contactsystem through a probe card ring 242. The probe card ring 242 isconnected to the frame 240 by fastening means such as screws 254.Between the probe card 60 and the probe card ring 242, a connectionmember formed of a nut 260 and a bolt 262 is provided for adjusting thegap between the probe card 60 and the probe card ring 242. Thisarrangement is an essential portion of the planarity adjustmentmechanism of the present invention.

[0059] The connection member can be configured by various otherstructure such as differential screws. The connection members (nuts 260)are provided at three or more locations on the probe card 60. Eachlocation of the nut 260 is preferably close to an outer edge of theprobe card 60 in such a way to form vertexes of a triangular orpolygonal shape. A rotation adjustment device 220 is preferably used foreasily and accurately rotating the nuts 260 for the planarityadjustment. The rotation adjustment device 220 is a specially made toolfor rotating the nut 260 with fine steps as will be described later.

[0060] A semiconductor wafer 300 to be tested is placed on a chuck 180of the substrate handler 400 (FIG. 1) such as a wafer prober. Althoughnot shown, it is known in the art that the frame 240 of the probecontact system and the housing of the substrate handler are mechanicallyconnected with each other. Thus, in this arrangement, the angle orinclination of the probe card and the contact substrate 20 is adjustedrelative to the probe card ring 242 (or frame 240 of the probe contactsystem), thereby adjusting the planarity of the tips of the contactors30.

[0061] The rotation of the nuts 260 causes vertical movements of thebolt 262, thereby changing the gap between the probe card 60 and theprobe card ring 242, and thus, between the contact substrate 20 and thesemiconductor wafer 300. In this arrangement, since the verticalpositions of the edges of the probe card 60 are changed at the threelocations or more locations, the heights of the contactors 30 on thecontact substrate 20 are accordingly adjusted to be flat relative to thesurface of the semiconductor wafer 300. In other words, since the probecard and the contact substrate 20 are fixedly attached to each other,the planarity of the contactors 30 are adjusted by changing theinclination of the probe card relative to the probe card ring 242, i.e.,the frame 240 of the system.

[0062] As an example, the gap sensor 290 is a capacitance sensor tomeasure capacitance between the sensor (electrode) 290 and the oppositeelectrode 292. The measured capacitance value is a function of thedistance between the two electrodes. An example of such a gap sensor isa model HPT-500-V offered by Capacitec, Inc., 87 Fichburg Road, Ayer,Mass. By monitoring the gap size between the sensor 290 and theelectrode 292 measured by the gap measurement instrument 280, anoperator rotates the nuts 260 with use of the rotation adjustment device220 in such a way that the gap at each of three or more locationsbecomes identical to one another.

[0063]FIG. 7 is a perspective view showing an upper surface of the probecard 60 and the probe card ring 242 in the probe contact system of thepresent invention. The probe card ring 242 is attached to the frame 240of the probe contact system by the fastening means such as screws 254.The nuts (connection members) 260 for the planarity adjustment areprovided at least three locations of the outer edge of the probe card60. Such positions of the nuts 260 preferably correspond to vertexes ofa regular triangle. FIG. 7 also shows the screws 250 which fixedlyattach the contact substrate 20 to the probe card 60.

[0064]FIG. 10 shows an example of arrangement associated with the nut 60formed on the surface of the probe card 60. The rotation adjustmentdevice 220 has an opening at the bottom (FIG. 8C) to fit with the nuts260 on the probe card 60. The probe card 60 has radial scales or marksaround the nuts 260 for easily observing the degree of rotation of thenut 60 by the rotation adjustment device 220. The probe card 60 also haspeg holes 264 to receive therein pegs 225 of the rotation adjustmentdevice 220.

[0065] FIGS. 8A-8C show, respectively, a top view, a front view and abottom view of the rotation adjustment device 220 of the presentinvention. As shown in FIG. 8B, the rotation adjustment device 220 isbasically configured by a top knob 221, a lower knob 222, and a knobbase 223. In FIG. 8A, the top knob 221 has a mark M on the top so thatthe operator knows the degree of rotation in combination with the radialscale 262 provided on the probe card 60 (FIG. 10). The top knob 221 andthe lower knob 222 are fixed by, for example screws, through fasteningholes 221 a. For avoiding slippage, the side surface of the top knob 221is provided with notches or gripping tapes.

[0066] As shown in FIG. 8B and 8C, the knob base 223 and the lower knob222 are rotatably connected with each other. The knob base 223 has pegs225 at its bottom to be inserted in the peg holes 264 on the probe card60. Thus, when in use, the knob base 223 stays on the probe card 60while the top knob 221 and lower knob 222 rotate on the knob base 223for adjusting the nut 260. The top knob 221 has a lower extended portion221 b having an opening 221 c. The nut 260 fits in the opening 221 c sothat the nut 260 is rotated by the rotation of the top knob 221 andlower knob 222.

[0067] FIGS. 9A-9G show exploded views of the rotation adjustment device220 of the present invention. The top knob 221 of FIG. 9A has the lowerextended portion 221 b which reaches the nut 260 on the probe card 60when adjusting the planarity. The lower knob 222 of FIG. 9D has manyretaining holes 235 to receive therein plungers 233 of FIG. 9C andsprings 232 of FIG. 9B. Although not shown, the bottom of the retainingholes 235 are reduced in the diameter so that only the lower tips of theplungers 233 can be projected from the bottom surface of the lower knob222. The plungers 233 are made of low friction or lubricated plasticsuch as Acetel or Delin supplied by DuPont.

[0068] The knob base 223 of FIG. 9F has a large number of radial grooves236 on the upper surface. When assembled, the lower tips of the plungers233 engage in the grooves 236 by the downward force of the springs 232.The pitch of the retaining holes 235 on the lower knob 222 and the pitchof the radial grooves 236 on the knob base 223 are designed to beslightly different from each other. Thus, when rotating the nut 250, therotation adjustment device 220 creates very small steps of rotation byengagement of the plungers 233 in the grooves 236 while giving clicks tothe operator.

[0069] The knob base 223 is attached to the lower knob 222 by means of atop retaining ring 234 of FIG. 9E and a lower retaining ring 238 of FIG.9G. The top retaining ring 234 with a flange 237 is inserted in thelower knob 222 from a top opening thereof and retained in the lowerposition of the lower knob 222. By connecting the top retaining ring 234and the lower retaining ring 238 while sandwiching the knob base 223between the lower knob 222 and the lower retaining ring 238, the knobbase 223 is rotatably attached to the lower knob 222 and the top knob221.

[0070]FIG. 11 is a cross sectional view showing a further example of theprobe contact system of the present invention having a planarityadjustment mechanism. In this example, an intermediate ring 246 isprovided between the probe card 60 and the probe card ring 242. Theintermediate ring 246 and the probe card 60 are attached to each otherby fastening means such as screws 258 (FIG. 12). The planarityadjustment mechanism (for example, connection member formed with nuts260 and bolts 262) is provided in a manner to connect the intermediatering 246 and the probe card ring 242 with each other at three or morelocations.

[0071] Similar to the example of FIGS. 6 and 7, the rotation of the nuts260 causes vertical movements of the bolt 262, thereby changing the gapbetween the intermediate ring 246 (probe card 60) and the probe cardring 242, and thus, between the contact substrate 20 and thesemiconductor wafer 300. In this arrangement, the vertical positions ofthe intermediate ring 246, i.e., the outer edges of the probe card 60are changed at the three or more locations. Therefore, the tips of thecontactors 30 on the contact substrate 20 are adjusted to be flatrelative to the surface of the semiconductor wafer 300. In this example,the probe card and the contact substrate 20 are fixedly attached to eachother, and the probe card and the intermediate ring are fixedly attachedto each other. Thus, the planarity of the contactors 30 are adjusted bychanging the inclination of the probe card 60 attached to theintermediate ring 246 relative to the surface of the probe card ring242, i.e., the frame 240 of the probe contact system.

[0072]FIG. 12 is a perspective view showing an upper surface of theprobe card 60, intermediate ring 246, and the probe card ring 242 in theprobe contact system of the present invention. The probe card ring 242is attached to the frame 240 of the probe contact system by thefastening means such as screws 254. The nuts (connection members) 260for the planarity adjustment are formed at three locations on theintermediate ring 246 at positions of vertexes of the triangle. The nuts60 connect the intermediate ring 246 to the probe card ring 242 in sucha way to adjust the gap therebetween.

[0073] Similar to the example of FIG. 10, the intermediate ring 246 mayinclude radial scales around the nuts 260 and peg holes 264 for easy andaccurate rotation of the nuts 260 with use of the rotation adjustmentdevice 220. FIG. 12 also shows the screws 250 which fixedly attach thecontact substrate 20 to the probe card 60.

[0074]FIG. 13 shows a further example of the probe contact system havinga planarity adjustment mechanism of the present invention. In thisexample, the planarity adjustment mechanism is an automatic system foradjusting distances between the contact substrate and the semiconductorwafer or reference plate. The adjustment mechanism includes motors 420for rotating the nuts 260 based on control signals from a controller430. The controller 430 produces the control signals by calculating themeasured gaps from the gap measurement instrument 280.

[0075] In the foregoing description of the present invention, althoughthe probe card ring 242 and the intermediate ring 246 are circularlyshaped, these members can have any shape such as a square frame. What isnecessary for these members is to couple between the probe card 60 andthe housing or frame of the probe contact system or substrate handlersuch as a wafer prober.

[0076] According to the present invention, the probe contact system iscapable of adjusting the distances between tips of contactors and thesurface of the semiconductor wafer under test or reference plate. Theplanarity adjustment mechanism is capable of adjusting the distancesbetween the contact substrate and the semiconductor wafer so that all ofcontactors on the contact substrate contact the surface of thesemiconductor wafer at substantially the same time with substantiallythe same pressure.

[0077] The planarity adjustment mechanism to be used in the probecontact system of the present invention includes the rotation adjustmentdevice for rotating the nuts on the probe card with fine steps therebyadjusting the distances between the contact substrate and thesemiconductor wafer easily and accurately. The planarity adjustmentmechanism of the present invention can be configured as an automaticsystem by incorporating the motors for driving the nuts on the probecard and the controller generating control signals for the motors on thebasis of the gaps measured by the gap sensors.

[0078] Although only a preferred embodiment is specifically illustratedand described herein, it will be appreciated that many modifications andvariations of the present invention are possible in light of the aboveteachings and within the purview of the appended claims withoutdeparting the spirit and intended scope of the invention.

What is claimed is:
 1. A planarity adjustment mechanism for a probe contact system for establishing electrical connection with contact targets, comprising: a contact substrate having a large number of contactors mounted on a surface thereof; a probe card for mounting the contact substrate for establishing electrical communication between the contactors and a test head of a semiconductor test system; means for fixedly mounting the contact substrate on the probe card; a probe card ring attached to a frame of the probe contact system for mechanically coupling the probe card to the frame; and a plurality of connection members for connecting the probe card to the probe card ring at three or more locations on the probe card, the connection member being adjustable for changing a gap between the probe card and the probe card ring.
 2. A planarity adjustment mechanism for a probe contact system as defined in claim 1, further comprising a gap sensor for measuring a gap between the contact substrate and a target substrate at predetermined locations of the contact substrate where the target substrate includes a semiconductor wafer to be tested and a reference plate prepared for adjusting the planarity.
 3. A planarity adjustment mechanism for a probe contact system as defined in claim 1, further comprising a rotation adjustment device for adjusting the connection member so that the gap between the probe card and the probe card ring is regulated, thereby adjusting the distances between the tips of the contactors and the contact target to be identical to one another.
 4. A planarity adjustment mechanism for a probe contact system as defined in claim 1, further comprising a conductive elastomer provided between the contact substrate and the probe card for electrically connecting the contact substrate and the probe card.
 5. A planarity adjustment mechanism for a probe contact system as defined in claim 1, wherein the connection member for connecting the contact substrate and the probe card is configured by bolts and nuts.
 6. A planarity adjustment mechanism for a probe contact system as defined in claim 1, wherein the connection member for connecting the contact substrate and the probe card is configured by differential screws.
 7. A planarity adjustment mechanism for a probe contact system as defined in claim 2, wherein the gap sensor determines the gap between the contact substrate and the target substrate by measuring capacitance between the gap sensor and an opposing electrode.
 8. A planarity adjustment mechanism for a probe contact system as defined in claim 2, wherein the gap sensor is provided either on the upper surface of the target substrate or the bottom surface of the contact substrate.
 9. A planarity adjustment mechanism for a probe contact system as defined in claim 2, wherein the reference plate is made of a ceramic or alumina substrate having electrodes at positions opposite to the gap sensor.
 10. A planarity adjustment mechanism for a probe contact system as defined in claim 1, wherein the reference plate is a metal plate for adjusting the planarity of the contactors on the contact substrate in such a way that all of the tips of the contactors contact the surface of the reference plate at substantially the same time with substantially the same pressure.
 11. A planarity adjustment mechanism for a probe contact system as defined in claim 1, wherein each of the three locations of the connection members on the probe card corresponds to a vertex of a regular triangle.
 12. A planarity adjustment mechanism for a probe contact system as defined in claim 3, wherein the connection member for connecting the probe card and the probe card ring is configured by bolts and nuts, and the nuts are rotatably supported on the surface of the probe card, and wherein the rotation adjustment device having a bottom opening which engages with the nut is placed on the surface of the probe card for rotating the nuts in such a way that the gaps between the contact substrate and the target substrate at a plurality of locations become identical to one another.
 13. A planarity adjustment mechanism for a probe contact system as defined in claim 12, wherein the rotation adjustment device is formed of a top knob, a lower knob and a knob base wherein the top knob and the lower knob are mechanically connected to each other while the lower knob and the knob base are rotatably attached to each other, and wherein the knob base is fixedly engaged with the probe card while the top knob having a lower extended portion having the bottom opening rotates the nut to adjust the gap at each of the three locations.
 14. A planarity adjustment mechanism for a probe contact system as defined in claim 13, wherein the lower knob of the rotation adjustment device is provided with a plurality of retaining holes for mounting therein plungers and springs in such a way the lower tips of the plunger protrude from a bottom surface of the lower knob by resilience produced by the springs, and the knob base of the rotation adjustment device is provided with a plurality of radial grooves so that the lower tips of the plunger engages with the grooves when the upper and lower knobs are rotated, and wherein the pitch of the retaining holes and the pitch of the radial grooves are different from one another.
 15. A planarity adjustment mechanism for a probe contact system as defined in claim 14, wherein the plungers are made of low friction plastic or lubricated plastic.
 16. A planarity adjustment mechanism for a probe contact system as defined in claim 4, further comprising a support frame provided between the contact substrate and the conductive elastomer for supporting the contact substrate wherein the connection member is extended between the probe card and the support frame.
 17. A planarity adjustment mechanism for a probe contact system as defined in claim 4, wherein the conductive elastomer is comprised of a silicon rubber sheet and metal filaments running in a vertical direction so as to establish communication only in the vertical direction.
 18. A planarity adjustment mechanism for a probe contact system for establishing electrical connection with contact targets, comprising: a contact substrate having a large number of contactors mounted on a surface thereof; a probe card for mounting the contact substrate for establishing electrical communication between the contactors and a test head of a semiconductor test system; means for fixedly mounting the contact substrate on the probe card; an intermediate ring attached to an outer area of the probe card; a probe card ring attached to a frame of the probe contact system for mechanically coupling the probe card to the frame through the intermediate ring; and a plurality of connection members for connecting the intermediate ring to the probe card ring at three or more locations on the intermediate ring, the connection member being adjustable for changing a gap between the intermediate ring and the probe card ring.
 19. A planarity adjustment mechanism for a probe contact system as defined in claim 18, further comprising a gap sensor for measuring a gap between the contact substrate and a target substrate at predetermined locations of the contact substrate where the target substrate includes a semiconductor wafer to be tested and a reference plate prepared for adjusting the planarity.
 20. A planarity adjustment mechanism for a probe contact system as defined in claim 18, further comprising a rotation adjustment device for adjusting the connection member so that the gap between the intermediate ring and the probe card ring is regulated, thereby adjusting the distances between the tips of the contactors and the contact target to be identical to one another.
 21. A planarity adjustment mechanism for a probe contact system as defined in claim 18, further comprising a conductive elastomer provided between the contact substrate and the probe card for electrically connecting the contact substrate and the probe card.
 22. A planarity adjustment mechanism for a probe contact system as defined in claim 19, wherein the gap sensor determines the gap between the contact substrate and the target substrate by measuring capacitance between the gap sensor and an opposing electrode.
 23. A planarity adjustment mechanism for a probe contact system as defined in claim 19, wherein the gap sensor is provided either on the upper surface of the target substrate or the bottom surface of the contact substrate.
 24. A planarity adjustment mechanism for a probe contact system as defined in claim 18, wherein the reference plate is made of a ceramic or alumina substrate having electrodes at positions opposite to the gap sensor.
 25. A planarity adjustment mechanism for a probe contact system as defined in claim 20, wherein the connection member for connecting the intermediate ring and the probe card ring is configured by bolts and nuts, and the nuts are rotatably supported on the surface of the intermediate ring, and wherein the rotation adjustment device having a bottom opening which engages with the nut is placed on the surface of the probe card for rotating the nuts in such a way that the gaps between the contact substrate and the target substrate at three or more locations become identical to one another.
 27. A planarity adjustment mechanism for a probe contact system as defined in claim 18, further comprising a support frame provided between the contact substrate and the conductive elastomer for supporting the contact substrate wherein the connection member is extended between the probe card and the support frame.
 28. A planarity adjustment mechanism for a probe contact system for establishing electrical connection with contact targets, comprising: a contact substrate having a large number of contactors mounted on a surface thereof; a probe card for mounting the contact substrate for establishing electrical communication between the contactors and a test head of a semiconductor test system; means for fixedly mounting the contact substrate on the probe card; a probe card ring attached to a frame of the probe contact system for mechanically coupling the probe card to the frame; a plurality of connection members for connecting the probe card to the probe card ring at three or more locations on the probe card, the connection member being adjustable for changing a gap between the probe card and the probe card ring; a gap sensor for measuring a gap between the contact substrate and a target substrate at predetermined locations of the contact substrate; a controller for generating a control signal based on a detection signal from the gap sensor indicating a size of the gap between the contact substrate and the target substrate; and a motor for driving the connection member based on the control signal from the controller.
 29. A planarity adjustment mechanism for a probe contact system as defined in claim 18, wherein the gap sensor determines the gap between the contact substrate and the target substrate by measuring capacitance between the gap sensor and an opposing electrode.
 30. A planarity adjustment mechanism for a probe contact system as defined in claim 28, wherein the gap sensor is provided either on the upper surface of the target substrate or the bottom surface of the contact substrate. 